Method for the manufacture of aluminum to be used for aluminothermic purposes



Nov. 24, 1942.

METHOD F STERN FOR ALUMINO-THERMIC PURPOSES Filed March 3, 1942 OR THE MANUFKCTURE" OF ALUMINUM TO BE USED IN'VENTOR= Max .Szfern ATTORNEY as for'the production of ferro alloys a comparatively achieved byv keeping the scrap.

Patented Nev. 24, 1942 umrsp, srA'rss PATENT, omce METHOD Fort ummm 'rns s To as u an roa summomirror-errataor AL THEBMIC PURPOSES p Max Stern, Kcw Gardens, N. .Y. Application March 3, 1942, Serial No. 433,188

' 2 Claims. (c1. 1H5)- The invention relates to a method for the A manufacture of aluminum to be used for aluminat-hermic purposes.

The metal, therefore, must be in a more or less comminuted form or consist'of particles of a small size. claritys sake be referred to as fthermite-aluminum" in the course of this specification.

Many methods for the production of this kind of aluminum are'known.

according to these known methods, for instance, a molten bath of aluminumis cast into granules or the molten metal is poured into a cylindrical press provided with a perforated bottom and pressed through the apertures of this This type of aluminum may for order to obtain particles of the desired is now ready for use. The Y bottom or the aluminum is mechanically comminuied.

Ifthe aluminum is used for the production of general thermite mixtures a disintegration to the size of -20 mesh/sq. inches is required, whereor pure molybdemetals such as chromium, vanadium,

num and titanium by'alumino-thermic reduction a coarser product is desired.

It is the object of this invention to produce thermite aluminum directly from aluminum scrap such as borings, turnings, chippings and grindings.

It is -a further object of the invention to entireiy obviate in the production of thermite aluminum the customary remelting procedure and to thereby avoidmelting losses which vary betweenii to 20%.

It is also an important object of the invention to avoid the excessive costs taminated products.

It is a further object of the invention to avoid and drawbacks of mechanical comminution leading to strongly conlosses of time and difllculties involved in the rethe contaminations. This may be advantageously in motion and in view the invention in its the following process 5 at a temperature of about 450-600" heating the same simultaneously to a temperature of about 200-250 0.

As soon as the impurities are removed and the the temperature'is raised to about 450-600 C. By the combined influence of the mechanical movement and this temperature the scrap changes its mechanical status entirely and becomes brittle to such an extent that it freely decomposes into small fragments of a varying size. The decomposed fragments are separatedin size; the

scrap is dry,

thus obtained product coarser portion is returned into the process.

.A device for carrying out the invention in the form of a rotary'fumace is shown in the attached drawing.

The rotary furnace onsis'ts of a preferably cast-iron cylinder 0 which is supported at an inclination of about 5" to assure the gradual transport of the charge through the furnace. The cylinder is surrcundui by a heating jacket I) which is heated encased in furnace heads a and d; the combustion gases escape. into chimney e.

The aluminum scrap charge is introduced through hopper i into the feed portion of the kiln; a perforated cylinder 0 is mounted within the discharge section of charge hoppers k, l are provided for cylinder a and for cylinder 9. By a suitable regulation of the burners m a temperature of approximately.

C. is maintained in the first part and C. is maintained a temperature of about 450-800 in the discharge part of the furnace.

. The contaminated aluminum chippings, tumings, borings or grindings are fed into the rotating furnace a from hopper f. The scrap is conveyed into the first section of the furnace and heated to about zoo-250 c. The organic matter, oil and the water are completely removed. Thecleaned and dried scrap is then slowly conducted into the zone of the furnace which is maintained C. By the combined influence of the motion imparted to the scrap through the rotation of the furnace and the specific temperature the deoiled and dried scrap undergoes a surprising change of its mefifi'chanical status.

a brittle and decomposes It becomes highlyfragile and of a varying size By the control of the speed of rotation the size of the fragments can be regulated insofar as the percentage of finer fragments may be inhy burners m. The feed end as well as the discharge end of the rotary kiln a are I the same. Separate disfreely into fine fragments a to about 450600 creased with an increase tion.

The finely comminuted material is then conveyed into cylinder g which is provided with a perforated wall g acting as a separating screen. This cylinder is exchangeable. The perforations are chosen in accordance with the desired size of the final product. The major portion of the treated material in the desired size falls into hopper k and is ready for use, The residual coarse portion is discharged into hopper f and returned to the feed for renewed treatment.

I claim:

1. Method for the manufacture of aluminum to be used for alumini-thermic purposes comprising transporting aluminum scrap successively through a zone heated to a temperature of about 200 to 250 C. and thenlthroug'h a zone heated C. keeping the scrap during its the said zones in continuous of the speed of rotapassage through motion, removing from the scrap in theflrst zone the impurities, producing in the second zone within the scrap a state of extreme brittleness, decomposing the scrap hereby into fragments of a diflerent size and separating from the same particles of a desired size.

2. Method for the manufacture of thermite aluminum comprising transporting aluminum scrap successively through a zone heated to a temperature of about 200 to 250 and through a zone heated to about 450-600 C., keeping the scrap during its passage through the said zones in continuous motion, removing from the scrap in the first zone the impurities, producing in the second zone within the scrap a state of extreme brittleness, decomposing the scrap hereby into fragments of a diflerent size, separating from the same particles of a desired size and returning the coarse particles for renewed treatment.

MAX STERN. 

